This invention relates in general to switches for switching one or more channels of radiation and in particular to a switch employing a coating partially reflective of radiation.
A prior art distributed matrix switch is shown in FIG. 1. A distributed matrix switch allows one of many output ports to pick up signals out of any one of the input ports. This type of signal routing device is widely used in fiber optic networks for configuring the optical signal distribution. A matrix switch of size 4xc3x974 is selected in FIG. 1 for illustration. 101-104 are four 1xc3x974 optical splitters used to equally or unevenly split the input power to four channels, e.g. 131(1)-134(1) of splitter 101. Each of the four channels of each splitter is grouped together with a corresponding channel of each of the remaining three splitters to form four groups of four output channels each. For example, channels 131(1), 131(2), 131(3), 131(4) are grouped together to form a group. The four channels of each group are respectively optically connected to four inputs of a switch, such as switch 111, so that the four outputs of all four splitters are connected to all four switches 111, 112, 113, 114. Therefore, the signal of the input ports I-1 to I-4 can reach any switch.
The prior art switch shown in FIG. 1 is disadvantageous since splitters are just as expensive as optical switches. Having to employ a large number of splitters to form a distributed matrix switch adds to the costs and increases the integration complexity and size. It is therefore desirable to provide an improved switch which is simpler and less expensive than the matrix switch of FIG. 1 described above.
This invention is based on the recognition that the above-described conventional matrix switch can be simplified by employing a partially reflective coating or wavelength selective filter which permits the splitting function to be incorporated into the switch as well, thereby significantly reducing the cost and the packaging size. One or more optical components may be used, where each component includes an optical coating or wavelength selective filter that partially reflects and partially passes different portions of an input radiation beam. By causing a receiving channel to receive a portion of a selected beam passed by a component by means of the optical coating or filter of that component, a switching function is performed.
One embodiment of the invention is in a form of a switch comprising a plurality of optical components, each component including an optical coating that reflects a first portion of an input beam of radiation and passes a second portion of the input beam; and receiving means including a receiving channel for receiving the second portion of an input beam passed by a selected component of the plurality of components.
Another embodiment of the invention is a distributed matrix switch comprising n sets of optical components, each set including m components, n, m being positive integers, each component including an optical coating that reflects a first portion of a corresponding input beam of radiation and passes a second portion of the input beam; n groups of optical paths, each group including (mxe2x88x921) paths for connecting the m components of a corresponding set of components, each path connecting the ith component to the (i+1)th component in the corresponding set, i ranging from 1 to (mxe2x88x921), so that radiation passed by the ith component becomes the input beam to the (i+1)th component; and receiving means including m receiving channels, each channel for receiving the second portion of an input beam passed by one of the components in the n sets of components; said receiving means including means for causing each of the in receiving channels to receive the second portion of the input beam passed by a selected one of the plurality of components.